Add 'cache' to default SAST excluded paths list

Problem to solve

We try to reduce false positives in common security scans by including generic ignores in our SAST_EXCLUDED_PATHS variable. We should be conservative with these to avoid false negatives but there are some good candidates to consider, such as cache which recently came up by a customer

Intended users

User experience goal

Less false positives with a default configuration

Proposal

Add cache to the default SAST_EXCLUDED_PATHS value

Documentation

Update https://docs.gitlab.com/ee/user/application_security/sast/index.html#vulnerability-filters with new value

What does success look like, and how can we measure that?

Less false positives with a default configuration

What is the type of buyer?

GitLab Core